Furnace



FIG. 1 is an end elevational view of a furnace showing my new design;

FIG. 2 is a side elevational view of the opposite side being a substantial mirror image thereof;

FIG. 3 is an elevational view of the end opposite that shown in FIG. 1,

FIG. 4 is a top plan view thereof.

The design is that of a wood burning furnace. 

The ornamental design for a furnace, as shown and described. 